Semiconductor processing using energized hydrogen gas and in combination with wet cleaning

ABSTRACT

A method of fabricating a semiconductor device. The method comprises subjecting a substrate having formed thereon photoresist layer to a plasma hydrogen, the substrate further having formed thereon a sacrificial layer; contacting the photoresist layer with a photoresist removal solution; subjecting the sacrificial layer to a plasma hydrogen; and contacting the sacrificial material layer with an etchant solution.

FIELD

Embodiments of the present invention relate to fabricating semiconductordevices using energized hydrogen gas in combination with wet chemistrycleaning to effectively remove a photoresist layer and/or a sacrificialfill layer.

BACKGROUND

Integrated circuits are made by forming on a semiconductor substratelayers of conductive material that are separated by dielectric(insulation) layers. Vias and/or trenches are etched in the dielectriclayers and are filled with a conducting material to electrically connectthe separated conductive layers. The vias and/or trenches filled withthe conductive materials may be referred to as interconnects.

Photoresist materials have wide use in the semiconductor fabricationindustry including masking and defining particular regions or areas onsubstrates or layers. Sacrificial materials have been used in making alithographic process more uniform and efficient in the semiconductorfabrication industry. Sacrificial materials and photoresist have beenused in the fabrication of semiconductor devices, for example, in dualdamascene metal interconnects as sacrificial via fill material and maskfor lithography process. Dual damascene metal interconnects may enablereliable low cost production of integrated circuits using sub 0.25micron process technology. Before such interconnects can realize theirfull potential, however, problems related to the process for making themmust be addressed. One problem involves the lithography for definingdual damascene vias and trenches. Sacrificial materials and photoresistmaterials are used throughout the lithography processes. The ability toremove these materials is crucial for the semiconductor processing.After the vias and trenches are formed, the sacrificial materials andthe photoresist materials need to be removed without removing otherlayers of the device, e.g., without removing or affecting the dielectriclayer and/or the surface of the silicon substrate. Additionally,photoresist materials have been used in ion implantations for makingsource/drain regions and/or source/drain extensions for various devices.After the source/drain regions and/or source/drain extensions arecreated, the photoresist materials need to be removed without affectingthe substrate or other layers on the substrate.

Another problem relates to the selectivity of certain materials, whichare used to make semiconductor devices and/or dual damascene devices, tothe etch chemistry used to etch the vias and trenches. At times, it'scrucial to remove a particular layer while not affecting another layer.Another problem yet, relates to removing the sacrificial materialsand/or the photoresist materials used during processing.

SUMMARY

Exemplary embodiments of the present invention pertain to methods offabricating semiconductor devices using energized hydrogen gas incombination with wet chemistry cleaning to effectively remove aphotoresist and/or sacrificial materials. The photoresist is typicallyused throughout the fabrication of semiconductor devices, e.g., to makevias and trenches and to mask undoped and define doped area. Thesacrificial material is also used throughout the fabrication ofsemiconductor devices, e.g., when making dual damascene interconnects.Alternatively, the embodiments provide methods to remove photoresistwithout affecting other functional layers or the substrate that thephotoresist layer associates with. The embodiments provide such featuresusing an energized hydrogen gas cleaning in combination with a wetchemistry cleaning.

In one embodiment, a method pertains to fabricating a semiconductordevice which comprises creating a via in a dielectric layer formed on asubstrate; filling the via, and optionally, the surface of thedielectric layer with a sacrificial material; forming and patterning aphotoresist layer on the sacrificial material to define a trench for thesemiconductor device; forming the trench; removing the photoresist layerafter the trench is formed; and subjecting the substrate to plasmahydrogen gas for a predetermined amount of time followed by contacting abuffered hydrogen fluoride (HF) solution to the substrate to remove thesacrificial material without substantially affecting the dielectriclayer.

In another embodiment, a method pertains to fabricating a semiconductordevice which comprises creating a via in a dielectric layer formed on asubstrate; filling the via, and optionally, the surface of thedielectric layer with a sacrificial material; forming and patterning aphotoresist layer on the sacrificial material to define a trench for thesemiconductor device; forming the trench; removing the photoresist layerafter the trench is formed; placing the substrate in a strip module andexposing the substrate to a hydrogen plasma for a predetermined amountof time; and removing the substrate from the strip module, placing thesubstrate in a wet cleaning module and dispensing a hydrogen fluoride(HF) solution over the substrate. The hydrogen plasma and the HFsolution remove the sacrificial material without substantially affectingthe dielectric layer.

In another embodiment, a method pertains to removing a photoresist layerwhich comprises subjecting the photoresist layer to a plasma hydrogen;and contacting the photoresist layer with a photoresist removal solution(e.g., sulfuric acid and hydrogen peroxide mixture). In anotherembodiment, the method of removing the photoresist layer mentioned(subjecting the photoresist layer to a plasma hydrogen; and contactingthe photoresist layer with a photoresist removal solution such assulfuric acid and hydrogen peroxide mixture) is applied to the formationof a semiconductor device where the photoresist is used for ionimplantation in the process of making source/drain regions orsource/drain extension of the device. In one embodiment, a substrate isprovided, a gate dielectric is formed on the substrate; a gate electrodeis formed on the gate dielectric; and spacer walls are optionally formedon the sides of the gate dielectric and the gate electrode. Ionimplantation is used to form source/drain regions in the substrate. Inone embodiment, a p-type dopant (e.g., boron) is used to form a PMOSdevice (Positive Channel Metal Oxide Semiconductor device) and an n-typedopant (e.g., phosphorous, arsenic, or antimony) is used to form an NMOSdevice (Negative Channel Metal Oxide Semiconductor device). During theion implantation process, a photoresist layer is used to define areasfor the doping. After the ion implantation, the photoresist layer isremoved by (i) subjecting the substrate to plasma hydrogen followed by(ii) contacting the photoresist layer to a photoresist removal solutionsuch as sulfuric acid and hydrogen peroxide mixture.

In another embodiment, a method pertains to removing a sacrificialmaterial layer which comprises subjecting the sacrificial material layerto a plasma hydrogen; and contacting the sacrificial material layer withan etchant solution (e.g., hydrogen fluoride solution).

In another embodiment, a method pertains to fabricating a semiconductordevice which comprises subjecting a substrate having formed thereonphotoresist layer to a plasma hydrogen, the substrate further havingformed thereon a sacrificial layer; contacting the photoresist layerwith a photoresist removal solution; subjecting the sacrificial layer toa plasma hydrogen; and contacting the sacrificial material layer with anetchant solution.

The embodiments also pertain to some exemplary systems that can be usedto practice one or more aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood more fully from the detaileddescription given below and from the accompanying drawings of variousembodiments of the invention, which, however, should not be taken tolimit the invention to the specific embodiments, but are for explanationand understanding only. In the drawings:

FIG. 1 illustrates an exemplary semiconductor device;

FIGS. 2-9 illustrate a cross-section of exemplary structures that mayresult after certain processes used to make a semiconductor device inaccordance to embodiments of the present invention;

FIG. 10 illustrates an exemplary embodiment of a system that can be usedto practice embodiments of the present invention;

FIGS. 11-13 illustrate an exemplary embodiment of a wet cleaning modulethat can be part of the system shown in FIG. 10 that can be used topractice embodiments of the present invention; and

FIG. 14 illustrates an exemplary embodiment of a dry stripping modulethat can be part of the system shown in FIG. 10 that can be used topractice embodiments of the present invention.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details are set forth. It will be evident, however, to oneskilled in the art that the embodiments of present invention may bepracticed without these specific details. In other instances, specificapparatus structures and methods have not been described so as not toobscure the present invention.

Exemplary embodiments of the present invention pertain to methods offabricating semiconductor devices using energized hydrogen gas incombination with wet chemistry cleaning to effectively remove aphotoresist and/or sacrificial materials. The photoresist is typicallyused throughout the fabrication of semiconductor devices, e.g., to makevias and trenches and to mask undoped and define doped area. Thesacrificial material is also used throughout the fabrication ofsemiconductor devices, e.g., when making dual damascene interconnects.Examples of sacrificial materials include sacrificial light material(SLAM), ACCUFILL™ and DUO™ Spin-on sacrificial via fill materials(ACCUFILL and DUO are trademarks of Honeywell Electronic Materials), orother sacrificial material such as Bottom Anti Reflective Coating (BARC)such as AR2 BARC from by Shipley. Alternatively, the embodiments providemethods to remove photoresist without affecting other functional layers(e.g., a dielectric layer) or the substrate (e.g., silicon) that thephotoresist layer associates with. The embodiments provide such featuresusing an energized hydrogen gas cleaning in combination with a wetchemistry cleaning.

In making semiconductor devices, sacrificial materials and photoresistmaterials have been used, for example, in fabricating dual damascenemetal interconnects. These materials have been used in making ordefining dual damascene vias and trenches in conjunction withlithography processes for the semiconductor devices. Additionally, thephotoresist materials have been used in doping processes where thephotoresist materials are used to mask undoped area or define dopedarea. The ability to effectively remove these materials withoutaffecting other functional layers is crucial for the semiconductorprocessing. In one embodiment, the photoresist material is removed usingan energized hydrogen gas in a dry stripping module and alternatively,an energized hydrogen gas in a dry stripping module followed by a wetcleaning in a wet cleaning module using a suitable chemistry solution.Removing the photoresist material using such embodiments preventsoxidation or loss of dopants to the surface of the substrate or otherlayers on the substrate. In another embodiment, the sacrificial materialis removed using an energized hydrogen gas in a dry stripping modulefollowed by a wet cleaning in a wet cleaning module using a wetchemistry solution that removes oxide such as a diluted hydrogenfluoride solution.

FIG. 1A illustrates a semiconductor device 2000 (e.g., a transistor)formed in a conventional manner. The device 2000 includes a substrate2002 having a channel region 2012, source and drain regions 2010, gatedielectric 2006, gate electrode 2004, and spacer walls 2008. Methods offorming the device 2000 are well known in the art. Many processes ofmaking the device 2000 requires the use of a photoresist layer 2001 as amask to define exposed and non-exposed a areas. For instance, aphotoresist mask may be placed over the gate electrode 2004 when an ionimplantation process is taking place to form the source and drainregions 2012. After the implantation, the photoresist material needs tobe removed.

In one embodiment, a photoresist mask is used to define regions on thesubstrate 2002 for the formation the source and drain regions 2010. Inone embodiment, the device 2000 is a PMOS type of device and thus thesource and drain regions 2010 are of p-type source/drain regions. Insuch embodiment, exemplary p-type dopants that can be to form thesource/drain regions 2010 include boron, beryllium, or magnesium. Inanother embodiment, the device 2000 is an NMOS type of device and thusthe source and drain regions 2010 are of n-type source/drain regions. Insuch embodiment, exemplary n-type dopants that can be to form thesource/drain regions 2010 include arsenic, phosphorous, or antimony.Methods of forming the source/drain regions 2010 or the associatedsource/drain extension (not shown) are known in the art. In any of theconventional methods, one or more photoresist layers 2001 are used tomask and expose (or define) certain regions of the substrate 2002 sothat the appropriate source/drain regions 2010 can be formed by ionimplantation. After the ion implantation process, the photoresist layeris removed.

Under current technology, the photoresist material is removed using adry strip chemistry process that utilizes oxygen plasma. It is knownthat the photoresist layer may become damaged or oxidized due to thevarious implantation processes in forming the semiconductor device 2000such that a hard crust 2001-C is formed on the top layer of thephotoresist layer 2001 (FIG. 1B). Thus, to completely remove thephotoresist layer, the crust 2001-C needs to be removed as well as thebulk 2001-B of the photoresist layer. Removing both the crust 2001 -Cand the bulk 2001 -B of the photoresist layer 2001 under the currenttechnology causes oxidation and loss of dopants of the surface ofsubstrate 2002 and other layers on the substrate 2002 (e.g., the gateelectrode and a dielectric layer, not shown). Removing the photoresistunder the current technology is known to cause oxidation to the surfaceof the substrate 2002 by at least about 7 angstrom under the mostcareful control. The oxidation in turn causes a loss of dopant in thesubstrate 2002 and thus affect the source and drain regions 2010 formedby ion implantation.

For semiconductor devices made using 65 nm and beyond technologies,photoresist removal without oxidation or loss of dopants on thesubstrate or other layers is very important. Oxidation of the substratewill lead to dopant loss and in the 65 nm and beyond technologies as thedopants are very close to the surface and thus any oxidation will leadto the dopant loss.

In one embodiment, the photoresist layer 2001 is removed using ahydrogen plasma process in a dry strip module (an exemplary embodimentof a dry strip module is described herein and below). The hydrogenplasma process does not cause oxidation to the surface of the substrate2000 or other similar layers that may be formed on the substrate 2000.The hydrogen plasma process thus does not cause lost of dopant to thesubstrate 2000 or other layers. Removing the photoresist layer 2001using the hydrogen plasma process in a dry strip module may be slowerthan conventionally done. In one embodiment, to speed up the photoresistremoval process, a wet cleaning process utilizing a suitable wetphotoresist chemistry solution, such as sulfuric acid and hydrogenperoxide mixture (SPM) solution, is used following the hydrogen plasmaremoval process. In one embodiment, the wet photoresist chemistrysolution includes 4 parts sulfuric acid and 1 part hydrogen peroxide.The wet cleaning process takes place in a wet cleaning module in whichan exemplary embodiment is described herein and below.

In one embodiment, the hydrogen plasma process removes the crust 2001-Cof the photoresist layer 2001 and the wet cleaning process removes thebulk 2001-B of the photoresist layer 2001. In one embodiment, the drystrip module and the wet cleaning module are parts of an integrated tool(e.g., cluster tool), which can make the cleaning processes moreefficiently.

In many embodiments, devices such as that shown in FIG. 1 needelectrical interconnections to be established to the source/drainregions or the gate electrode of the devices. Vias and trenches may becreated through dielectric layers to establish a connection path to thesource/drain regions or the gate electrode of the devices. Additionally,many devices establish interconnection using dual damasceneinterconnects.

FIGS. 2-9 illustrate structures that may results from exemplaryembodiments of the present invention. The embodiments are presented inthe context of making a device that includes a dual damasceneinterconnect. These embodiments can be used for other similarsemiconductor structures that may not include dual damasceneinterconnect or that may include other suitable interconnect.

In FIG. 2, a first conductive layer 101 is formed on a substrate 1000.The substrate 1000 may be any surface generated when making asemiconductor device or an integrated circuit, upon which a conductivelayer may be formed. The substrate 1000 may be the substrate 2000previously described in FIG. 1. The first conductive layer 1101 istypically formed to allow electrical interconnect to the device or theintegrated circuit formed in the substrate 1000. The first conductivelayer 1101 may be the gate electrode 2004 shown in FIG. 1 or otherconductive feature communicable with the gate electrode 2004 or thesource/drain regions 2010. In one embodiment, the substrate 1000includes active and/or passive devices that are formed on a siliconwafer such as transistors, capacitors, resistors, diffused junctions,gate electrodes, local interconnects, etc . . . , such as the device2000 shown in FIG. 1. The substrate 1000 also may include insulatingmaterials (e.g., silicon dioxide, either undoped or doped withphosphorus (PSG) or boron and phosphorus (BPSG); silicon nitride;silicon oxynitride; or a polymer) (not shown) that separate such activeand passive devices from the conductive layer or layers that are formedon top of them, and may include previously formed conductive layers. Thesubstrate 1000 is typically made of a semiconductor material (e.g.,silicon monocrystalline silicon, silicon-on-insulator, silicon-germaniumor other suitable materials used in the field).

The conductive layer 1001 may be made from materials conventionally usedto form conductive layers for integrated circuits such as copper, copperalloy, aluminum or an aluminum alloy, and aluminum/copper alloy.Alternatively, the conductive layer 1001 may be made from dopedpolysilicon or a silicide, e.g., a silicide comprising tungsten,titanium, nickel or cobalt. In one embodiment, the conductive layer 1001includes a number of separate layers. The conductive layer 1001 maycomprise a primary conductor made from an aluminum/copper alloy that issandwiched between a relatively thin titanium layer located below it anda titanium, titanium nitride double layer located above it. Theconductive layer 1001 may also comprise a copper layer formed onunderlying barrier and seed layers.

In one embodiment, the conductive layer 1001 is formed by a chemicalvapor. In another embodiment, the conductive layer 1001 is formed by aphysical deposition process. In an embodiment where copper is used tomake the conductive layer 1001, a conventional copper electroplatingprocess may be used. Techniques for forming a conductive layer such asthe conductive layer 1001 are well known to those of ordinary skilled inthe art.

Also in FIG. 2, a barrier layer 1002 is formed on the conductive layer1001. In one embodiment, the barrier layer 1002 serves to prevent anunacceptable amount of copper, or other conductive metals, fromdiffusing into a dielectric layer 103. The barrier layer 1002 also actsas an etch stop to prevent subsequent via and trench etch processingfrom exposing the conductive layer 1001 to subsequent cleaningprocesses. In one embodiment, the barrier layer 1002 is made fromsilicon nitride and in other embodiments, made from materials that canserve the functions previously mentioned. Other examples for the barrierlayer 1002 include titanium nitride, silicon carbide, or siliconoxynitride.

In one embodiment, the barrier layer 1002 is formed from silicon nitrideand can be formed using a chemical vapor deposition process. The barrierlayer 1002 should be thick enough to perform its diffusion inhibitionand etch stop functions, but not so thick that it adversely impacts theoverall dielectric characteristics resulting from the combination of thebarrier layer 1002 and the dielectric layer 1003. In one embodiment, thethickness of the barrier layer 1002 is less than about 10% of thethickness of the dielectric layer 103.

In one embodiment, the conductive layer 1001 and barrier layer 1002 areplanarized after they are deposited. In one embodiment, the conductivelayer 1001 and barrier layer 1002 are planarized using a chemicalmechanical polishing (CMP).

In FIG. 2, a dielectric layer 1003 is formed on top of the barrier layer1002. In one embodiment, the dielectric layer 1003 comprises silicondioxide, which is deposited on the surface of the barrier layer 1002using a conventional method such as plasma enhanced chemical vapordeposition (PECVD) process. An exemplary silicon source that can be usedwith the PECVD process includes tetraethylorthosilicate (TEOS) as thesilicon source. In other embodiments, the dielectric layer. 1003 is madefrom other materials that can insulate one conductive layer fromanother. An example of a material that can be used to make thedielectric layer 1003 include an organic polymer selected from the groupthat includes polyimides, parylenes, polyarylethers, polynaphthalenes,and polyquinolines, or copolymers thereof. Examples of other organicdielectric materials include SiO-based dielectric, SiOCH, SiOF, andSpin-on-SiOCH. The dielectric layer 1003 can also be made of acommercially available polymer sold by Dow Chemicals under the tradename SiLK™ or those sold by Honeywell International, Inc., under tradenames FLARE™, GX3 and GX3P. The dielectric layer 1003 can also be madeof an inorganic dielectric material such as fluorinated silica glass(FSG) and phosphorous doped TEOS (pTEOS). In some embodiment, thedielectric layer 1003 comprises fluorinated silicon dioxide or a poroussilicon dioxide, e.g., silicon dioxide doped with carbon. Methods ofmaking or forming the dielectric layer 1003 are known to those skilledin the art. In one embodiment, the dielectric layer 1003 is formed tohave a thickness of between about 2,000 and about 20,000 angstroms.

Also in FIG. 2, after the dielectric layer 1003 is formed, a photoresistlayer 1030 is deposited and patterned or defined on top of thedielectric layer 1003 to define a via formation region for receiving asubsequently formed conductive layer that will contact the firstconductive layer 1001. The photoresist layer 1030 may be patterned ordefined using conventional photolithographic techniques, such as maskingthe layer of photoresist material, exposing the masked photoresist layerto light, then developing the unexposed portions.

FIG. 3 illustrates that a via 1007 is formed in the dielectric layer1003. In one embodiment, after the photoresist 1030 is patterned, thevia 1007 is etched through the dielectric layer 1003 down to the barrierlayer 1002. Conventional methods can be used to etch the dielectriclayer 1003 to form the via 1007. An example of such a method includes ananisotropic dry oxide etch process. In an embodiment when silicondioxide is used to form the dielectric layer 1003, the via is etchedusing a medium density magnetically enhanced reactive ion etching system(“MERIE system”) using fluorocarbon chemistry, which is known in theart.

After the via 1007 is formed, the photoresist layer 1030 is removed. Inone embodiment, the photoresist layer 1030 is removed using a hydrogenplasma process in a dry strip module. The hydrogen plasma process doesnot cause oxidation to the surface of the dielectric layer 1030 and/orthe substrate 1000 or other similar layers (not shown) that may beformed on the substrate 1000. In one embodiment, to speed up thephotoresist layer 1030 removal process, a wet cleaning process utilizinga wet resist chemistry solution, such as sulfuric acid hydrogen peroxidesolution, is used following the hydrogen plasma removal process. In oneembodiment, the wet resist chemistry solution includes 4 parts sulfuricacid and 1 part hydrogen peroxide. In one embodiment, the hydrogenplasma process may be used to remove the crust of the photoresist layer1030 and the wet cleaning process removes the bulk of the photoresistlayer 1030. The wet cleaning process takes place in a wet cleaningmodule (described below).

In FIG. 4, a sacrificial material is used to fill the via 1007. In oneembodiment, after the via 1007 is formed through the dielectric layer1003, the via 1007 is filled with a sacrificial material 1004. In oneembodiment, the sacrificial material 1004 has dry etch propertiessimilar to those of the dielectric layer 1003. The sacrificial material1004 may comprise a spin-on-polymer (SOP) or spin-on-glass (SOG), asacrificial light absorbing material (SLAM), or a similar SLAM materialwith a trade name DUO (made by Honeywell Electronic Materials). DUO isan organosiloxane polymer designed to absorb at 248 nm radiation. DUO isalso a hybrid of oxide (SiO) structures and organic components (e.g.,benzene ring, CH₃ and CH₂). In one embodiment, the sacrificial material1004 is deposited by spin coating to a thickness of about 500 and about3,000 angstroms of the material onto the surface of the device, usingconventional process steps. Although only a thin layer remains on thesurface of the device, such a spin coating process causes thesacrificial material 1004 to substantially, or completely, fill the via1007.

In FIG. 5, after the via 1007 is filled with the sacrificial material1004, a photoresist layer 1036 is applied on top of the sacrificialmaterial layer 1004, then patterned to define a trench formation region.The photoresist layer 1036 may be patterned using conventionalphotolithographic techniques. The photoresist layer 1036 may beinspected for accuracy and alignment prior to the trench formationprocess. Lithographic rework may be performed when the photoresist layer1036 is not patterned or aligned accurately or correctly. Forlithographic rework, the photoresist layer 1036 may be removed and a newphotoresist layer (not shown) may be deposited and patterned.

In one embodiment, when there is need for lithographic rework (e.g.,perhaps due to the fact that the photoresist layer 1036 is not formed orpatterned correctly or accurately) the photoresist layer 1036 is removedusing an ozonated organic acid solvent such as an ozonate acetic acidsolution so that the photoresist layer 1036 is removed without affectingthe sacrificial layer 1004. In one embodiment, the substrate 1000 withthe photoresist layer 1036 is treated in a wet cleaning module with theozonated organic acid solvent to remove the photoresist layer 1036without affecting the sacrificial layer 1004. More details of theprocesses of selectively removing the photoresist without affecting thesacrificial material can be found in a co-pending patent applicationentitled “ORGANIC SOLVENTS HAVING OZONE DISSOLVED THEREIN FORSEMICONDUCTOR PROCESSING UTILIZING SACRIFICIAL MATERIALS” by StevenVerhaverbeke, which has an attorney docket number AMAT 8907/W-C/W-C/JB1,and which is incorporated by reference herein by it entirety.

In FIG. 6, a trench 1006 is formed following the photoresist layer 1036patterning and any necessary lithographic inspection and/or rework.

As shown in FIG. 6, the trench 1006 is etched into the dielectric layer1003. The etching process is applied for a time sufficient to form thetrench 1006 with a desired depth. In one embodiment, the etch chemistrychosen to etch the trench 1006 removes the sacrificial material 1004 ata slightly faster rate than it removes the dielectric layer 1003, toavoid formation of defects. The trench 1006 may be etched using the sameequipment and etch chemistry that had been used previously to etch thevia 1007. As with the via etch step, the barrier layer 1002 may act asan etch stop during the trench etching process, protecting theunderlying conductive layer 1001 from the etch step and any subsequentashing or cleaning steps. In addition, the presence of any portion ofthe sacrificial material 1004 that remains at the bottom of the via 1007after the trench etch step may help ensure that the conductive layer1001 will not be affected by the trench etch process.

Because forming the trench 1006 requires etching into the sacrificialmaterial 1004 as well as the dielectric 1003, it is desirable that thesacrificial material and the dielectric material have similar materialthat have similar etching properties with the sacrificial materialpreferably has slightly faster etch rate than the dielectric material.Additionally, by filling the via 1007 with the sacrificial material 1004that has dry etch characteristics like those of the dielectric layer1003, the trench lithography process may effectively have asubstantially “hole-free” surface, similar to one without the vias 1007.In one embodiment, the sacrificial material 1004 is selected so that ithas an etch chemistry similar to the dielectric layer 1003 so that thetrench 1006 may be etched into the dielectric layer 1003 at a rate thatis almost as fast as the sacrificial material 1004 is removed. Such aprocess protects the underlying barrier layer 1002 during the trench1006 etching. Such a process also permits the use of a trench etchchemistry that produces superior trench and via profiles without havingto consider the effect such etch chemistry might have on the selectivitybetween the dielectric layer 1003 and the barrier layer 1002.

In an embodiment, the dielectric layer 1003 comprises silicon dioxideand the barrier layer 1002 comprises silicon nitride, an etch chemistryto be used to etch the trench 1006 should be one that does not provide ahigh selectivity to silicon dioxide and to silicon nitride. In addition,because the process of the present invention reduces the amount of timeduring which the barrier layer 1002 is etched during the trench etchprocess, the thickness of barrier layer 1002, e.g., a silicon nitridelayer, when initially deposited, is only minimally reduced (e.g., onlyless than about 400-600 angstroms is etched).

After the trench 1060 is etched, the photoresist 1036 and thesacrificial material 1004 and residues that may remain on the device'ssurface and inside the vias 1007 are removed or cleaned (FIG. 7). In oneembodiment, the photoresist layer 1036 is removed using a dry strippingmodule (an exemplary embodiment of such a module is described herein andbelow) in which an energized hydrogen gas is used to remove thephotoresist layer. In one embodiment, the energized hydrogen gascleaning occurs at a temperature of about 100-250° C., a pressure lessthan 100 Torr (e.g., 1-10 Torr) and for about 2 minutes.

The sacrificial material 1004 is removed first treating the sacrificialmaterial 1004 with an energized hydrogen gas (in a dry stripping module)and then treat the sacrificial material 1004 with a wet cleaning using ahydrogen fluoride solution in a wet cleaning module. In one embodiment,the wet cleaning is carried out using a diluted hydrogen fluoridesolution containing about 1-6% hydrogen fluoride. In one embodiment, theenergized hydrogen gas cleaning occurs at a temperature of about200-250° C., a pressure less than 100 Torr (e.g., 1-10 Torr) and forabout 2 minutes.

The barrier layer 1002 protects the first conductive layer 1001 fromexposure to the solvents and/or oxidizing environment used when cleaningthe trench. After the photoresist layer 1036 and the sacrificialmaterial 1004 are removed, the barrier layer 1002 can be “partiallyremoved” in which the portion of the barrier layer 1002 that separatesthe via 1007 from the first conductive layer 1001 is removed to exposethe first conductive layer 1001 to form the structure shown in FIG. 8.The barrier layer 1002 can be removed using conventional method knownthose skilled in the art such as RIE (reactive ion etching). The barrierlayer 1002 removal may be followed by a short wet etch (which employs anetch chemistry that is compatible with the material used to formconductive layer 1001) to clear etch residue from the surface of theconductive layer 1001. When copper is used to make the conductivelayers, that portion of barrier layer 1002 should be removed, using acopper compatible chemistry, before any copper electroplating step isapplied to fill the via 1007 and the trench 1006.

In FIG. 9, following the barrier layer 1002 partially removed, thetrench 1006 and the via 1007 are filled with a second conductive layer1005. The second conductive layer 1005 may comprise any of the materialsidentified above in connection with the first conductive layer 1001(e.g., copper or copper formed over a copper/tantalum seed layer). Thesecond conductive layer 1005 may comprise the same conductive materialas the first conductive layer 1001, or may comprise a conductivematerial different from the material used to make the first conductivelayer 1001. After the second conductive layer 1005 is formed, a CMPprocess may be used to planarize the surface of the second conductivelayer 1005.

FIG. 10 illustrates an apparatus or system 100 that can be used topractice various embodiments of the present invention. It is to beunderstood that other equipments or systems can be used to practiceembodiments of the present invention and that the system 100 is only forillustration purpose and are not to be construed as limitations of theembodiments of the present invention. The system 100 can be used for astripping (ashing) process previously mentioned, for instance, the firsttreatment in the removal process of the photoresist layer 1030, thephotoresist layer 1036, or the sacrificial layer 1004. The system 100can also be used for a wet cleaning process as previously mentioned, forinstance, the second treatment in the removal process of the photoresistlayer 1036 or the sacrificial layer 1004 or to remove or selectivelyremove the photoresist layer 1036 using an organic acid solvent havingozone dissolved therein when lithographic rework is necessary. Thesystem 100 allows for the integration of two different cleaning modulesso that the cleanings can be done in an efficient manner as well asmaintaining the cleanings under the same atmospheric condition. Thesystem 100 may be a part of a bigger system used for manufacturing of asemiconductor device or an integrated circuit.

In one embodiment, the system 100 includes a central transfer chamber102 having a wafer-handling device 104 contained therein. The wafer tobe transferred or processed can be the substrate 1000 previouslydescribed. Directly attached to the transfer chamber 102 is a singlewafer wet cleaning module 200 and a strip (ash) module 400. The wetcleaning module 200 and the strip module 400 are each connected to thetransfer chamber 102 through a separately closable opening. In anembodiment of the present invention, a second wet cleaning module 200Band/or a second strip (ash) module 400B are also coupled to the transferchamber 102. In an embodiment of the present invention, the transferchamber 102 is maintained at substantially atmospheric pressure (makingit an atmospheric transfer chamber) during operation. In one embodiment,the module 200, 200B, 400, and 400B, each can be operated undersubstantially atmospheric condition thus the transfer chamber 102 can bemaintained at such similar condition.

In an embodiment of the present invention, the atmospheric transferchamber 102 can be opened or exposed to the atmosphere of asemiconductor fabrication “clean room” in which it is located. In suchan embodiment, the transfer chamber 102 may contain an overhead filter,such as a hepafilter to provide a high velocity flow of clean air or aninert ambient such as nitrogen (N₂), to prevent contaminants fromfinding their way into the atmospheric transfer chamber. In otherembodiments, the atmospheric transfer chamber 102 is a closed system andmay contain its own ambient, of clean air or an inert ambient, such asnitrogen gas.

The transfer chamber 102 includes a wafer handler (or wafer handlingrobot), which can transfer a wafer from one module to another. In anembodiment of the present invention, the wafer handler is a single robot104 with two wafer handling blades 114 and 116 which both rotate about asingle axis 119 coupled to the end of a single arm 120. The robot 104can be said to be a dual blade single arm, single wrist robot. The robot104 moves on a track 122 along a single axis in transfer chamber 102.

Also coupled to the transfer chamber 102 is at least one waferinput/output module 130 or pod for providing wafers to the system 100and for taking wafers away from the system 100. In an embodiment of thepresent invention, the wafer input/output module 106 is a front openingunified pod (FOUP) which is a container having a slideable and sealabledoor and which contains a cassette of between 13-25 horizontally spacedwafers. The transfer chamber 102 contains a sealable access door 110,which slides vertically up and down or horizontally across to enableaccess into and out of the transfer chamber 102. In an embodiment of thepresent invention, the system 100 includes two FOUP's, 106 and 108 onefor providing wafers into the system 100 and one for removing completedor processed wafers from the system 100. However, a wafer can beinputted and outputted from the same FOUP, if desired. A second accessdoor 112 is provided to accommodate a second FOUP 108. Each access doorcan be attached to the counter part door on each FOUP so that when thetransfer chamber access door 110 and 112 slides open, it opens the doorof the FOUP to provide access for the robot into the FOUP. The FOUP'scan be manually inserted onto the system 100 or a wafer stocking system114, such as a Stocker, having multiple FOUP's in a rail system can beused to load and remove FOUP's from the system 100.

The system 100 may be configured to include or communicate with otherprocessing modules such as a chemical vapor deposition module fordepositing a film (e.g., a dielectric film or a sacrificial film, aconductive film), an etch module for forming the via or trench, and aphotolithographic process tool for patterning the photoresist layer,etc... The system 100 may be configured so that the system 100 includesor can communicate to a sub-atmospheric platform to accommodate theprocessing modules that operate under a sub-atmospheric condition.

In one embodiment, a system computer 124 is coupled to and controls eachof the wet clean module 200 and the strip module 400 (or otheradditional modules) as well as the operation of the transfer chamber 102and the robot 104. The system computer 124 controls the operation of thesystem 100 such as the operation of each of the modules, the transferchamber 102, the cleaning and drying processes that take place in anyone of the modules, and the flow of a wafer (or a plurality of wafers)through the system 100 and /or to control the process within a differentmodule.

In one embodiment, the system computer 124 includes and/or can execute amachine or computer readable instructions that perform various methods(including the operations of the associated modules or apparatus) offabricating a semiconductor devices in accordance to embodiments of thepresent invention. In one embodiment, the instructions perform a methodthat comprises creating a via in a dielectric layer formed on asubstrate; filling the via, and optionally, the surface of thedielectric layer with a sacrificial material; forming and patterning aphotoresist layer on the sacrificial material to define a trench for thesemiconductor device; forming the trench; removing the photoresist layerafter the trench is formed; and subjecting the substrate to plasmahydrogen gas for a predetermined amount of time followed by contacting abuffered hydrogen fluoride (HF) solution to the substrate to remove thesacrificial material without affecting the dielectric layer. In anotherembodiment, the method includes creating a via in a dielectric layerformed on a substrate; filling the via, and optionally, the surface ofthe dielectric layer with a sacrificial material; forming and patterninga photoresist layer on the sacrificial material to define a trench forthe semiconductor device; forming the trench; removing the photoresistlayer after the trench is formed; placing the substrate in a stripmodule and exposing the substrate to a hydrogen plasma for apredetermined amount of time; and removing the substrate from the stripmodule, placing the substrate in a wet cleaning module and dispensing ahydrogen fluoride (HF) solution over the substrate. The hydrogen plasmaand the HF solution remove the sacrificial material withoutsubstantially affecting the dielectric layer. In another embodiment, themethod includes removing a photoresist layer which further comprisessubjecting the photoresist layer to a plasma hydrogen; and contactingthe photoresist layer with a photoresist removal solution. In anotherembodiment, the method includes removing a sacrificial material layercomprises subjecting the sacrificial material layer to a plasmahydrogen; and contacting the sacrificial material layer with an etchantsolution (e.g., hydrogen fluoride solution). In another embodiment, themethod includes subjecting a substrate having formed thereon photoresistlayer to a plasma hydrogen, the substrate further having formed thereona sacrificial layer; contacting the photoresist layer with a photoresistremoval solution; subjecting the sacrificial layer to a plasma hydrogen;and contacting the sacrificial material layer with an etchant solution

An example of a single wafer cleaning module 200 which can be used asthe wet cleaning module 200 and 200B is illustrated in FIGS. 11-13.FIGS. 11-13 illustrate a single wafer cleaning apparatus 200, whichutilizes acoustic or sonic waves to enhance a cleaning. The single wafercleaning apparatus 200 can be used to remove the photoresist layer 1036,in an embodiment, for lithographic rework, using an organic acid solventhaving ozone dissolved therein. The single wafer cleaning apparatus 200can also be used to clean the substrate 1000 throughout the processingwhenever wet cleaning is required. The single wafer cleaning apparatus200 can also be used to treat the photoresist layer and/or thesacrificial material in the second treatment after these layers havebeen treated with the energized hydrogen gas or hydrogen plasmatreatment as previously mentioned.

The single wafer cleaning apparatus 200 shown in FIG. 11 includes aplate 202 with a plurality of acoustic or sonic transducers 204 locatedthereon. The plate 202 maybe made of aluminum but can be formed of othermaterials such as but not limited to stainless steel and sapphire. Theplate 202 is maybe coated with a corrosion resistant fluoropolymer suchas Halar or PFA. The transducers 204 are attached to the bottom surfaceof the plate 202 by an epoxy 206. In an embodiment of the presentinvention, the transducers 204 cover substantially the entire bottomsurface of the plate 202 as shown in FIG. 12 and alternatively, cover atleast 80% of the plate 202. The transducers 204 generate sonic waves inthe frequency range e.g., between 400 kHz and 8 MHz. In an embodiment ofthe present invention the transducers 204 are piezoelectric devices. Thetransducers 204 create acoustic or sonic waves in a directionperpendicular to the surface of a wafer 208 that is placed in the singlewafer cleaning apparatus 200.

A substrate or wafer 208 is held at distance of about 3 mm above the topsurface of the plate 202. The wafer 208 can be the substrate 1000 or thesubstrate 2000 previously described. The wafer 208 is clamped by aplurality of clamps 210 face up to a wafer support 212 which can rotatethe wafer 208 about its central axis. The wafer support 212 can rotateor spin the wafer 208 about its central axis at a rate between 0-6000rpm. In the apparatus 200, only the wafer support 212 and the wafer 208are rotated during use whereas the plate 202 remains in a fixedposition. Additionally, in the apparatus 200, the wafer 208 is placedface up wherein the side of the wafer with patterns or features such astransistors faces towards a nozzle 214 for spraying cleaning chemicalsthereon and the backside of the wafer 208 faces the plate 202.Additionally, as shown in FIG. 13, the transducers covered plate 202 hasa substantially same shape as the wafer 208 and the plate 202 covers theentire surface area of the wafer 208. The apparatus 200 can include asealable chamber 201 in which the nozzle 214, the wafer 208, and theplate 202 are located as shown in FIG. 11.

In an embodiment of the present invention, during use, deionized water(DI-H₂O) is fed through a feed through channel 216 of the plate 202 andfills the gap between the backside of the wafer 208 and the plate 202 toprovide a water filled gap 218 through which acoustic waves generated bythe transducers 204 can travel to the substrate 208. In an embodiment ofthe present invention DI water fed between the wafer 208 and the plate202 is degassed so that cavitation is reduced in the DI water filled gap218 where the acoustic waves are strongest thereby reducing potentialdamage to the wafer 208. In an alternative embodiment of the presentinvention, instead of flowing DI-H₂O through the channel 216 during use,cleaning chemicals, such as the organic acid solvent having ozonedissolved therein, hydrogen fluoride solution, or sulfuric acid hydrogenperoxide solution can be fed through the channel 216 to fill the gap 218to provide chemical cleaning of the backside of the wafer 208, ifdesired. Other suitable cleaning solvent can also be used.

Additionally during use, cleaning the chemicals and rinsing water suchas DI-H₂O, ozonated organic acid solvent, photoresist removal solution,or hydrogen fluoride are fed through a nozzle 214 to generate a spray220 of droplets which form a liquid coating 222 on the top surface ofthe wafer 208, in one embodiment, while the wafer 208 is spun. In thepresent embodiment, the liquid coating 222 can be as thin as 50-150micron. In one embodiment, one or more tanks 224 containing cleaning oneore more chemicals such as an organic acid solvent, acetic acid solvent,propionic acid solvent, and butyric acid solvent are coupled to theconduit 226, which feeds the nozzle 214. Alternatively, DI-H₂O, HF,photoresist removal solution, or other suitable solution may also becoupled to the conduit 226 through the tanks 224. There may be more thanthree or less than three tanks 224 shown in FIG. 11. In an embodiment ofthe present invention the diameter of the conduit 226 has a reducedcross-sectional area or a “Venturi” 228 in a line before the nozzle 214at which point a gas such as O₃ (ozone) is dissolved in the solution asit travels to the nozzle 214. The Venturi 228 enables a gas to bedissolved into a fluid flow at gas pressure less than the pressure ofthe liquid flowing through the conduit 226. The Venturi 228 createsunder pressure locally because of the increase in flow rate at theVenturi. The Venturi 228 and a gas source allow a treatment gas to bedissolved into a particular cleaning solution, which is particularlyuseful for certain cleaning process. For instance, the Venturi 228 andthe gas source allow O₃ to be dissolved into the organic acid solventfor selectively removing the photoresist layer. Other gases (e.g., N₂ orH₂) can also be used when suitable.

FIG. 14 illustrates a strip or dry cleaning module 400 of the system 100in accordance with an embodiment of the present invention. In thecleaning chamber 400 of the type illustrated in FIG. 14, an energizedprocess gas comprising cleaning gas is provided to clean a substrate 480held on a support 410 in a process zone 415. The support 410 supportsthe substrate 480 in the process zone 415 and may optionally comprise anelectrostatic chuck 412. Within or below the support 410, a heat source,such as infrared lamps 420, can be used to heat the substrate 430. Theprocess gas comprising a cleaning gas may be introduced through a gasdistributor 422 into a remote plasma generation zone 425 in a remotechamber 430. By “remote” it is meant that the center of the remotechamber 430 is at a fixed upstream distance from the center of a processzone 415 in the cleaning chamber 400. In the remote chamber 430, thecleaning gas is activated by coupling microwave or radio frequency (RF)energy into the remote chamber 430, to energize the cleaning gas andcause ionization or dissociation of the cleaning gas components, priorto its introduction through a diffuser 435, such as a showerheaddiffuser, into the process zone 415. Alternatively, the process gas maybe energized in the process zone 415. Spent cleaning gas and residue maybe exhausted from the cleaning chamber 400 through an exhaust system 440capable of achieving a low pressure in the cleaning chamber 400. Athrottle valve 425 in the exhaust 440 is used for maintaining a chamberpressure from about 150 mTorr to about 3000 mTorr.

In one embodiment, the remote chamber 430 comprises a tube shaped cavitycontaining at least a portion of the remote plasma zone 425. Flow of thecleaning gas into the remote chamber 430 is adjusted by a mass flowcontroller or gas valve 450. The remote chamber 430 may comprise wallmade of a dielectric material such as quartz, aluminum oxide, ormonocrystalline sapphire that is substantially transparent to microwaveand is non-reactive to the cleaning gas. A microwave generator 455 isused to couple microwave radiation to the remote plasma zone 425 of theremote chamber 430. A suitable microwave generation 455 is an “ASTEX”Microwave Plasma Generator commercially available from Applied Science &Technology, Inc., Woburn, Mass. The microwave generator assembly 455 maycomprise a microwave applicator 460, a microwave tuning assembly 465,and a magnetron microwave generator 470. The microwave generator may beoperated at a power level of about 200 to about 3000 Watts, and at afrequency of about 800 MHz to about 3000 MHz. In one embodiment, theremote plasma zone 425 is sufficiently distant from the process zone 415to allow recombination of some of the dissociated or ionized gaseouschemical species. The resultant reduced concentration of free electronsand charged species in the activated cleaning gas minimizes charge-updamage to the active devices on the substrate 480, and provides bettercontrol of the chemical reactivity of the activated gas formed in theremote plasma zone 425. In another embodiment, the center of the remoteplasma zone 425 is maintained at a distance of at least about 50 cm fromthe center of the process zone 415.

A cleaning process may be performed in the cleaning chamber 400 byexposing the substrate 480 to energized process gas comprising cleaninggas to treat the photoresist layer or the sacrificial material prior toremoving them using the wet cleaning module. In one embodiment, thecleaning gas is hydrogen and when energized as previously described, thehydrogen gas may be referred to as hydrogen plasma. The hydrogen plasmacan be used to treat a photoresist layer or a sacrificial layer duringtheir removal process as previously described.

The following sections describe exemplary embodiments of using thesystem 100 to treat or clean certain layers (e.g., photoresist layer orsacrificial layer) from a substrate.

In one embodiment, a photoresist layer such as the photoresist layer2001 on the substrate 2000 (FIGS. 1A-1B) is removed in accordance toembodiments of the present invention. Other photoresist layer includesthose that are used during a dopant or ion implantation processes suchthat removal of the photoresist requires the photoresist to be removedwithout oxidizing or affecting the dopant concentration of thesubstrate. The photoresist layer 2001 is first treated with a hydrogenplasma in the strip module 400 of the system 100 and is then wet cleanedwith a photoresist removal solution such as sulfuric acid hydrogenperoxide (SPM) solution in the wet cleaning module of the system 100.Thus, when a photoresist layer used during the fabrication process of asemiconductor device, such as the device 2000, where the photoresistlayer needs to be removed without affecting (e.g., oxidizing) thesubstrate or its associated layers in a way that will cause lost ofdopants, such photoresist layer can be removed using a hydrogen plasmafollowed by a wet cleaning process with a photoresist removal solutionsuch as sulfuric acid hydrogen peroxide (SPM) solution. In oneembodiment, in the hydrogen plasma treatment takes place in the stripmodule 400 of the system 100. In one embodiment, the wet cleaningprocess with the photoresist removal solution takes place in the wetcleaning module 200 of the system 100.

The substrate 2000 is shown in the chamber 400 as a wafer 480 (FIG. 14).The wafer 480 can be placed in the chamber 400 using the robot transferassembly 104. According to an embodiment of the present invention, acassette or FOUP of wafers including the substrate 2000 are placed in adocking station in the system 100. One or more of the wafers can be thesubstrate 2000. In one embodiment, the robot 104 removes the wafer 480from the FOUP 130 and places the wafer 480 into the single wafercleaning apparatus 400. The single wafer cleaning apparatus 400 is thensealed and the cleaning process begins. In one embodiment, the pressureof the single wafer cleaning apparatus 400 is substantially atatmospheric pressure.

The wafer 480 is exposed to an energized hydrogen gas. For a 5-literprocess chamber 400, a suitable gas flow rate comprises 3000 to 3500sccm of H₂. Heating the substrate 480 may improve the removal rate ofthe photoresist layer and may also improve the removal rate of someetchant residue in some embodiments.

In one embodiment, the photoresist layer 2001 is treated with thehydrogen plasma for about 2 minutes at a temperature of about 100-250°C. and a pressure less than or equal to about 100 Torr. In oneembodiment, the hydrogen gas is activated by coupling microwave or RFenergy into the remote chamber 430 to energize the hydrogen gas andcause ionization or dissociation of the hydrogen gas prior to itsintroduction through the diffuser 435 and into the process zone 415. Thehydrogen gas may be energized in the process zone 415, in anotherembodiment. The hydrogen gas flown into the remote chamber 430 can beadjusted by the mass flow controller gas valve 450. In one embodiment,the hydrogen gas is energized a power between about 200 to about 6000Watts. The hydrogen plasma removes the crust portion 2001-C on thephotoresist layer 2001 without oxidizing or causing lost to the dopantthat may have been implanted in the substrate 2000 or other layers.

It is to be noted that the photoresist layer 2001 needs not be treatedwith the hydrogen plasma in the strip module 400 but can be treated withthe hydrogen plasma using other known apparatus.

Following the hydrogen plasma treatment, the photoresist layer 2001 istreated with a photoresist removal solution in the wet cleaning chamber200. In one embodiment, after the hydrogen plasma treatment, thesubstrate 2000 is removed from the chamber 400 and is placed in the wetcleaning module 200 (using the robot 104). In the chamber 200, thephotoresist layer 2001 (the remaining bulk portion 2001-B) is treatedwith a photoresist removal solution such as the SPM solution. The wetcleaning may occur at a temperature of about 90-120° C. and atsubstantially atmospheric pressure. In one embodiment, the SPM solutionincludes 4 parts sulfuric acid and 1 part hydrogen peroxide. The SPM maybe premixed as a mixture prior to being dispensed into the cleaningchamber 200.

In one embodiment, the substrate 2000 is placed on the plate 202 of thechamber 200 with the side of the photoresist layer 2001 facing upwardtoward the nozzle 214. (The substrate 2000 may be shown as the wafer 208in FIG. 11). The transducer 204 is turned on. DI-H₂O is fed through thechannel 216 to fill the gap 218. The SPM solution is dispensed throughthe nozzle 214 to form a thin coating 222 on top of the substrate 2000and the photoresist layer 2001. The substrate 2000 may be spun while theSPM solution is being dispensed. The substrate 2000 may be treated withthe SPM solution for about 30 seconds to several minutes (e.g., 3minutes) to completely remove the photoresist layer 2001.

It is to be noted that the photoresist layer 2001 needs not be treatedwith the SPM solution in the chamber 200 but can be contacted with theSPM solution by other methods such as rinsing, splashing, or immersingas is well known in the art.

The photoresist layer 1030 and 1036 can also be removed using similarprocesses as described for the photoresist layer 2001. Thus, during anyparticular process of the fabrication of the device, the substrate 1000with the photoresist layer 1030 or the photoresist layer 1036 can beplaced in the system 100, in the strip module 400 for the hydrogenplasma treatment, and then in the wet cleaning chamber 200 for the wetcleaning similar to previously described.

In one embodiment, the single wafer cleaning apparatus 200 of the system100 is also used to selectively remove a photoresist layer such as thephotoresist layer 1036 for lithographic rework (or other purposes) sothat a new photoresist layer can be formed and patterned. Lithographicrework may be needed when the photoresist layer 1036 is not properlyaligned or not correctly patterned. In one embodiment, the photoresistlayer 1036 needs to be removed without affecting other layers especiallythe sacrificial layer 1004.

According to an embodiment of the present invention, a cassette or FOUPof wafers that need to be cleaned or treated are placed in a dockingstation in the apparatus 100. One or more of the wafers can be thesubstrate 1000 previously discussed. In one embodiment, the wafer 208 isthe substrate 1000 previously described that has the photoresist layer1036, which needs to be removed without affecting the sacrificial layer1004. The robot 104 removes the wafer 208 from the FOUP 130 and placesthe wafer into the single wafer cleaning apparatus 200. The single wafercleaning apparatus 200 is then sealed and the cleaning process begins.In one embodiment, the pressure of the single wafer cleaning apparatus200 is substantially at atmospheric pressure.

In one embodiment, to selectively remove the photoresist layer 1036, anorganic acid solvent (e.g., acetic acid, propionic acid, or butyricacid) having ozone gas dissolved therein is used to treat thephotoresist layer 1036. After the wafer 208 (which in the presentembodiment is the substrate 1000) is placed in the module 200, theorganic acid solvent having the ozone dissolved therein is dispensed atthe outlet 214 as the droplets 220 of ozone dissolved organic acid toform a thin coating 222 of ozone dissolved organic acid on top of thewafer 208. The wafer 208 is spun (for example at about 1000 rpm) whilethe ozone dissolved organic acid is being dispensed. In one embodiment,the ozone dissolved organic acid is a 99% acetic acid solution havingozone dissolved therein to about 100 ppm or greater (e.g., 200-400 ppmof ozone). In the present embodiment, the photoresist layer 1036 can beremoved at a rate of about 5 lim/min at room temperature. The organicacid solvent having ozone dissolved therein may be dispensed over thewafer 208 for about 20 seconds to several minutes (e.g., 2-3 minutes) toremove the photoresist layer 1036 without affecting the sacrificialmaterial (e.g., DUO or SLAM sacrificial material) 1004. A thickerphotoresist layer 1036 would require a little more time for thecleaning.

In another embodiment, a small amount of HF is added to the organic acidsolvent having ozone dissolved therein to remove contaminants that mayhave formed during the photoresist cleaning process. In one embodiment,about 2% of HF is included in the organic acid solvent having ozonedissolved therein.

The system 100 can also be used to remove a sacrificial material such asthe sacrificial material 1004 in accordance to embodiments of thepresent invention. The sacrificial material 1004 is first treated with ahydrogen plasma in the strip module 400 of the system 100 and is thenwet cleaned with an etching solution such as hydrogen fluoride solutionin the wet cleaning module of the system 100.

In one embodiment, the sacrificial material 1004 is treated with thehydrogen plasma for about 2 minutes at a temperature of about 200-250°C. and a pressure less than or equal to about 100 Torr. Similar topreviously described, the substrate 1000 is placed in the dry stripmodule 400 using the robot 104. The hydrogen plasma may react with theorganic compound of the sacrificial material to effect the removal ofthe sacrificial material. After the hydrogen plasma treatment, thesubstrate 1000 is removed from the chamber 400 and is placed in the wetcleaning module 200 similar to previously described and is treated withan etching solution such as hydrogen fluoride to completely remove thesacrificial material. In one embodiment, the hydrogen fluoride in thewet cleaning process removes the oxide portion of the sacrificialmaterial 1004. The wet cleaning may occur at a temperature of about90-120° C. and at substantially atmospheric pressure.

In one embodiment, the substrate 1000 is shown in the chamber 400 as awafer 480 (FIG. 14). The wafer 480 can be placed in the chamber 400using the robot transfer assembly 104. According to an embodiment of thepresent invention, a cassette or FOUP of wafers including the substrate1000 are placed in a docking station in the system 100. One or more ofthe wafers can be the substrate 2000. In one embodiment, the robot 104removes the wafer 480 from the FOUP 130 and places the wafer 480 intothe single wafer cleaning apparatus 400. The single wafer cleaningapparatus 400 is then sealed and the cleaning process begins. In oneembodiment, the pressure of the single wafer cleaning apparatus 400 issubstantially at atmospheric pressure.

The wafer 480 is exposed to an energized hydrogen gas. For a 5-literprocess chamber 400, a suitable gas flow rate comprises 3000 to 3500sccm of H₂. Heating the substrate 480 may improve the removal rate ofthe sacrificial layer.

In one embodiment, the sacrificial layer 1004 is treated with thehydrogen plasma for about 2 minutes at a temperature of about 100-250°C. and a pressure less than or equal to about 100 Torr. In oneembodiment, the hydrogen gas is activated by coupling microwave or RFenergy into the remote chamber 430 to energize the hydrogen gas andcause ionization or dissociation of the hydrogen gas prior to itsintroduction through the diffuser 435 and into the process zone 415. Thehydrogen gas may be energized in the process zone 415, in anotherembodiment. The hydrogen gas flown into the remote chamber 430 can beadjusted by the mass flow controller gas valve 450. In one embodiment,the hydrogen gas is energized a power between about 200 to about 6000Watts. The hydrogen plasma reacts with the organic compound of thesacrificial layer 1004 to remove the organic compound from the layer1004.

Following the hydrogen plasma treatment, the wafer is moved from thechamber 400 into the chamber 200 for wet cleaning. The wafer is placedon the plate 202 of the chamber 200 with the side of the photoresistlayer 2001 facing upward toward the nozzle 214. The transducer 204 isturned on. DI-H₂O is fed through the channel 216 to fill the gap 218.The HF solution is dispensed through the nozzle 214 to form a thincoating 222 on top of the wafer. The wafer may be spun while the HFsolution is being dispensed. The wafer may be treated with the HFsolution for about 30 seconds to several minutes (e.g., 2-3 minutes) tocompletely remove the sacrificial layer 1004.

It is to be noted that the photoresist layer 2001 needs not be treatedwith the hydrogen plasma in the strip module 400 but can be treated withthe hydrogen plasma using other known apparatus. It is also to be notedthat the sacrificial layer 1004 needs not be treated with the HFsolution in the chamber 200 but can be contacted with the HF solution byother methods such as rinsing, splashing, or immersing as is well knownin the art.

In any of the embodiments of the present invention, the dispensing ofthe ozone dissolved organic acid, the mixing of the acetic acid and theozone, the dispensing rate of the ozone dissolved organic acid, thedispensing of the HF solution, the dispensing or mixing of thephotoresist removal (e.g., SPM) solution, the hydrogen plasmageneration, the spinning rate of the wafer 208, as well as otheroperations associated with the apparatus 200 or 400 can be controlled bythe system computer 124.

Although the foregoing description has specified certain steps,materials, and equipments that may be used in such a method to make suchan integrated circuit, those skilled in the art will appreciate thatmany modifications and substitutions may be made. For example, althoughthe embodiments have been described in the context of making a dualdamascene device, the invention is not limited to that particularapplication. Accordingly, it is intended that all such modifications,alterations, substitutions and additions be considered to fall withinthe spirit and scope of the invention as defined by the appended claims.

1. A method of fabricating a semiconductor device comprising: creating avia in a dielectric layer formed on a substrate; filling the via, andoptionally, the surface of the dielectric layer with a sacrificialmaterial; forming and patterning a photoresist layer on the sacrificialmaterial to define a trench for the semiconductor device; forming thetrench; removing the photoresist layer after the trench is formed; andsubjecting the substrate to plasma hydrogen gas for a predeterminedamount of time followed by contacting a buffered hydrogen fluoride (HF)solution to the substrate to remove the sacrificial material withoutsubstantially affecting the dielectric layer.
 2. The method of claim 1wherein the photoresist layer is removed using an organic acid solventcomprising ozone.
 3. The method of claim 2 wherein a hydrogen fluoridesolution is added to the organic acid solvent comprising ozone.
 4. Themethod of claim 1 wherein the photoresist layer is removed using atreatment solution having about 99% acetic acid and ozone of about 100ppm or higher concentration.
 5. The method of claim 1 wherein removingthe photoresist further comprises one of contacting the substrate withan acetic acid having ozone dissolved therein solution, contacting thesubstrate with an propionic acid having ozone dissolved thereinsolution, and contacting the substrate with an butyric acid having ozonedissolved therein solution.
 6. The method of claim 1 wherein removingthe photoresist layer further comprises treating the substrate withhydrogen plasma.
 7. The method of claim 6 wherein removing thephotoresist layer further comprises contacting the substrate with aphotoresist removal solution following the treating of the substratewith hydrogen plasma.
 8. The method of claim 7 wherein photoresist isremoved at a temperature between about 90-120° C.
 9. The method of claim1 further comprising: filling the trench and the via with a conductivematerial.
 10. The method of claim 11 further comprising: forming aconductive layer on top of the substrate and below the dielectric layer.11. The method of claim 10 further comprising: forming an etch stoplayer on top of the conductive layer and below the dielectric layer andremoving the etch stop layer after the second photoresist layer and thesacrificial material are removed.
 12. A method of fabricating asemiconductor device comprising: creating a via in a dielectric layerformed on a substrate; filling the via, and optionally, the surface ofthe dielectric layer with a sacrificial material; forming and patterninga photoresist layer on the sacrificial material to define a trench forthe semiconductor device; forming the trench; removing the photoresistlayer after the trench is formed; placing the substrate in a stripmodule and exposing the substrate to a hydrogen plasma for apredetermined amount of time; removing the substrate from the stripmodule, placing the substrate in a wet cleaning module and dispensing ahydrogen fluoride (HF) solution over the substrate; wherein the hydrogenplasma and the HF solution remove the sacrificial material withoutsubstantially affecting the dielectric layer.
 13. The method of claim 12wherein removing the photoresist layer further comprising: placing thesubstrate in a third module; and dispensing an organic acid solventhaving ozone dissolved therein over the substrate to remove thephotoresist layer.
 14. The method of claim 13 wherein a hydrogenfluoride solution is added to the organic acid solvent comprising ozone.15. The method of claim 13 wherein the organic acid solvent having ozonedissolved therein includes about 99% acetic acid and about 100 ppm orhigher ozone.
 16. The method of claim 12 further comprising: filling thetrench and the via with a first conductive material after thephotoresist and the sacrificial material are removed.
 17. The method ofclaim 16 further comprising: forming a second conductive layer on top ofthe substrate and below the dielectric layer wherein the firstconductive layer interconnect with the second conductive layer throughthe via and the trench.
 18. The method of claim 17 further comprising:forming an etch stop layer on top of the second conductive layer andbelow the dielectric layer to protect the second conductive layer; andremoving the etch stop layer after the photoresist layer and thesacrificial material are removed and prior to filling the via and thetrench with the first conductive layer.
 19. A method for removing aphotoresist layer comprising: subjecting the photoresist layer to aplasma hydrogen; and contacting the photoresist layer with a photoresistremoval solution.
 20. The method as in claim 19 further comprising:placing a substrate having the photoresist layer formed thereon in a drystrip module to subject the photoresist layer to the plasma hydrogen;transferring the substrate to a wet cleaning module after the subjectingthe photoresist layer to the plasma hydrogen; and dispensing thephotoresist removal solution over the photoresist layer in the wetcleaning module.
 21. The method as in claim 20 wherein the dry stripmodule and the wet cleaning module are integrated into one system andwherein the dry strip module and the wet cleaning module are connectedthrough a transfer chamber included within the system.
 22. The method asin claim 19 wherein the photoresist removal solution includes a mixtureof sulfuric acid and hydrogen peroxide.
 23. A method for removing asacrificial material layer comprising: subjecting the sacrificialmaterial layer to a plasma hydrogen; and contacting the sacrificialmaterial layer with an etchant solution.
 24. The method as in claim 23further comprising: placing a substrate having the sacrificial materiallayer formed thereon in a dry strip module to subject the sacrificialmaterial layer to the plasma hydrogen; transferring the substrate to awet cleaning module after the subjecting the sacrificial material layerto the plasma hydrogen; and dispensing the etchant solution over thesacrificial material layer in the wet cleaning module.
 25. The method asin claim 24 wherein the dry strip module and the wet cleaning module areintegrated into one system and wherein the dry strip module and the wetcleaning module are connected through a transfer chamber included withinthe system.
 26. The method as in claim 23 wherein the etchant solutionincludes hydrogen fluoride.
 27. A method for fabricating a semiconductordevice comprising: subjecting a substrate having formed thereonphotoresist layer to a plasma hydrogen, the substrate further havingformed thereon a sacrificial layer; contacting the photoresist layerwith a photoresist removal solution; subjecting the sacrificial layer toa plasma hydrogen; and contacting the sacrificial material layer with anetchant solution.
 28. The method as in claim 27 further comprising:placing the substrate in a dry strip module to subject the sacrificiallayer to the plasma hydrogen; transferring the substrate to a wetcleaning module after the subjecting the sacrificial material layer tothe plasma hydrogen; and dispensing the etchant solution over thesacrificial material layer in the wet cleaning module.
 29. The method asin claim 28 wherein the dry strip module and the wet cleaning module areintegrated into one system and wherein the dry strip module and the wetcleaning module are connected through a transfer chamber included withinthe system.
 30. The method as in claim 27 wherein the etchant solutionincludes hydrogen fluoride.
 31. The method as in claim 27 furthercomprising: placing the photoresist layer a dry strip module to subjectthe photoresist layer to the plasma hydrogen; transferring the substrateto a wet cleaning module after the subjecting the photoresist layer tothe plasma hydrogen; and dispensing the photoresist removal solutionover the photoresist layer in the wet cleaning module.
 32. The method asin claim 31 wherein the dry strip module and the wet cleaning module areintegrated into one system and wherein the dry strip module and the wetcleaning module are connected through a transfer chamber included withinthe system.
 33. The method as in claim 27 wherein the photoresistremoval solution includes a mixture of sulfuric acid and hydrogenperoxide.
 34. The method as in claim 27 further comprising: placing thephotoresist layer a dry strip module to subject the photoresist layer tothe plasma hydrogen; transferring the substrate to a wet cleaning moduleafter the subjecting the photoresist layer to the plasma hydrogen;dispensing the photoresist removal solution over the photoresist layerin the wet cleaning module; transferring the substrate from the wetcleaning module to the dry strip module after dispensing the photoresistremoval solution over the photoresist layer; subjecting the sacrificiallayer to the plasma hydrogen; transferring the substrate to the wetcleaning module after subjecting the sacrificial material layer to theplasma hydrogen; and dispensing the etchant solution over thesacrificial material layer in the wet cleaning module.
 35. The method asin claim 34 wherein the dry strip module and the wet cleaning module areintegrated into one system and wherein the dry strip module and the wetcleaning module are connected through a transfer chamber included withinthe system.
 36. A method of fabricating a semiconductor devicecomprising: providing a substrate; forming a gate dielectric layer onthe substrate; forming a gate electrode on the dielectric layer; forminga first photoresist layer on the substrate to define a source and drainregions in the substrate and forming the source and drain regions in thesubstrate; removing the first photoresist layer after the source anddrain regions are formed, wherein removing the first photoresist layerfurther includes subjecting the substrate to hydrogen plasma and thencontacting the photoresist layer with a photoresist removal solution toremove the first photoresist layer.
 37. The method of claim 36 whereinremoving the photoresist removal solution includes sulfuricacid-hydrogen peroxide solution.
 38. The method of claim 36 furthercomprising: forming a dielectric layer on the substrate, wherein thesubstrate includes source and drain regions, the gate dielectric layer,and the gate electrode formed thereon; creating a via in the dielectriclayer formed on a substrate; filling the via, and optionally, thesurface of the dielectric layer with a sacrificial material; forming andpatterning a second photoresist layer on the sacrificial material todefine a trench for the semiconductor device; forming the trench;removing the second photoresist layer after the trench is formed; andremoving the sacrificial material after the trench is formed, whereinremoving the sacrificial material further includes subjecting thesubstrate to plasma hydrogen gas for a predetermined amount of timefollowed by contacting a buffered hydrogen fluoride (HF) solution to thesubstrate to remove the sacrificial material without substantiallyaffecting the dielectric layer.
 39. The method of claim 38 wherein thesecond photoresist layer is removed using an organic acid solventcomprising ozone.
 40. The method of claim 39 wherein a hydrogen fluoridesolution is added to the organic acid solvent comprising ozone.
 41. Themethod of claim 38 wherein the second photoresist layer is removed usinga treatment solution having about 99% acetic acid and ozone of about 100ppm or higher concentration.
 42. The method of claim 38 wherein removingthe second photoresist further comprises one of contacting the substratewith an acetic acid having ozone dissolved therein solution, contactingthe substrate with an propionic acid having ozone dissolved thereinsolution, and contacting the substrate with an butyric acid having ozonedissolved therein solution.
 43. The method of claim 38 wherein removingthe second photoresist layer further comprises treating the substratewith hydrogen plasma.